Technologies and Costs for Removal of Arsenic From Drinking Water

column. The Phase 3 Report noted that arsenic leakage was always greater from the onceregeneratedalumina than the virgin alumina. For the 5-minute EBCT runs, an average arsenicleakage (up to 3200 BV) of 0.3 and 1.4 Fg/L was observed for the virgin and once-regeneratedAlcoa CPN alumina runs. For the Alcan alumina at an EBCT of 5 minutes, average arsenicleakage (up to 3200 BV) was 0.2 and 1.3 Fg/L for the virgin and once-regenerated aluminaruns. After 3200 BV, the normal breakthrough curve started, so the effluent arsenic was notsolely due to leakage. Since the run length of 4300 BV and breakthrough equation were bothbased on the once-regenerated Alcoa CPN alumina, arsenic leakage was also estimated forthis alumina. The average arsenic leakage was 1.4 Fg/L It was assumed that the secondcolumn would exhibit the same leakage characteristics as the first column. Thus, arsenicleakage for the second column was assumed constant at 1.4 Fg/L. It was assumed that 1.4Fg/L would pass through both columns starting at the beginning of the run. The second columnwill probably remove some of the arsenic that is passing through the first column, so thisapproach likely overestimates the amount of arsenic leakage for the second column. However,since there was no way to estimate a breakthrough curve for the second column, it was notpossible to estimate arsenic in the effluent due to reduced adsorptive capacity. The arsenicleakage estimate was used to account for all arsenic that would pass through the secondcolumn - from both leakage and reduced adsorptive capacity. Thus, it likely underestimatesthe amount of arsenic that passed through the second column into the finished water. Thearsenic leakage was estimated using the following equation:As leakage = (1.4 Fg/L)(RL BV)(16,032 L/BV) Where RL = run length in BVFor a run length of 18,500 BV:As leakage = 415 gramsF. The available arsenic capacity of the second column is estimated by adding the arsenicleakage to the minimum arsenic capacity of the second column.Available Arsenic Capacity of Column 2 = 3814 grams + 415 grams = 4229 gramsD-18